1. Field of the Invention
The present invention relates to a rubber crawler mainly used for a running unit of construction or civil engineering machinery (hereinafter merely referred to as vehicle). More particularly, the invention relates to a rubber crawler which adopts a novel structure as a tensile reinforcement.
2. Description of the Related Art
In the structure of the rubber crawler used in the conventional vehicles, as shown in FIG. 1, a core bar a which forms a running path of a rotating wheel is embedded in a rubber b with a constant spacing in a lengthwise direction of the rubber crawler, and steel cords d in a row are also embedded in the rubber in order to surround outsides of left and right wing portions c of the core bar a to resist tensile force applied to the rubber crawler. A top surface of a projection ao formed in the core bar a becomes a running surface of the rotating wheel. Because relatively thin cord wires are twisted in the steel cord d, rust is generated due to moisture invading the rubber from the outside, and finally breakage of steel cord d is not prevented from occurrence.
Japanese Patent Laid-Open Publication No. 2000-313371 is an example in which the steel cord is not used. As shown in FIG. 2, in the rubber crawler of Japanese Patent Laid-Open Publication No. 2000-313371, rods f which corresponds to the left and right wing portions are used. Pairs of the rods f and f are inserted through blocks g and g from left and right ends of the rods f and f. Coupling links h and h are fitted into the rods g and g. A row of the blocks g is arranged to be shifted regarding the other row of the blocks g. The top surfaces of the blocks g as a whole become the running surface of the rotating wheel. The coupling links h and h are employed instead of a conventional steel cord.
In the rubber crawler of Japanese Patent Laid-Open Publication No. 2000-313371, the rod f, the block g, and the coupling link h must be regularly combined. This demands careful assembly and the production efficiency is questioned. The block g and the coupling link h are need to be assembled from the left and light sides of the rod f. This means a great width of a work space. In addition, when the rod f, the block g, and the coupling link h are arranged at predetermined positions of a mold of the rubber crawler after the assembly, the block g or the coupling link h might disengage from the rod f. No space exists where the rod f is fitted into the block g or the coupling link h in the mold. These features show that the production efficiency is not good. Generally, dealing with the rod f by hand is not recommended. In this point, in the technology of Japanese Patent Laid-Open Publication No. 2000-313371, manual handling of the rod f is indispensable for fitting the rod f into the block g or the coupling link h from a widthwise direction of the rod f. Such handling affects the adhesion of the rods f to the rubber.